The present invention relates generally to ferromagnetic core inductors, and more particularly to a sealed connection to inductor coils in a sealed housing.
Inductors are passive electronic components which store electrical energy in magnetic fields. Ferromagnetic core inductors have two principal components: a rigid core of ferromagnetic or ferrimagnetic material, and a conductor, usually wound about the core in one or more turns. Some inductors include multiple coils dedicated to distinct voltage phases. Inductors are characterized by an inductance L which resists changes in current through the conductor. According to Faraday's law, the magnetic flux induced by changing current through the conductor generates an opposing electromotive force opposing the change in voltage. For a ferromagnetic inductor with a rectangular cross-section toroidal core,
  L  =      0.01170    ⁢                  ⁢          N      2        ⁢    h    ⁢                  ⁢          log      10        ⁢                  ⅆ        2                    ⅆ        1            Where L=inductance (μH), μ0=permeability of free space=4π*10−7 H/m, N=number conductor turns, h=core height (in), d1=core inside diameter (in), and d2=core outside diameter (in).
Many inductors use conductors formed of litz wire. Litz wire is made up of bundles of individually insulated wires. A single litz wire may comprise hundreds of these individually insulated parallel wires.
Real-world inductors are not perfectly energy efficient. During operation, ferromagnetic core inductors radiate heat both from core losses, and from series resistance. Accordingly, inductors in commercial or industrial applications may be cooled utilizing liquid or immersion cooling. Liquid and immersion cooling configurations house the inductor within a sealed housing containing a coolant fluid. At least one connection with the conductor extends through the housing, allowing the inductor to be contacted externally.
Litz wires are difficult to seal when utilizing liquid or immersion cooling. Because each litz wire is made up of many individually insulated wires, a litz wire connection through a sealed inductor housing may allow coolant fluid to leak between individually insulated wires.